Laser Raman spectroscopy when combined with the ability to alter individual residues in a protein provides a powerful method of investigating biomolecular mechanisms. Examples discussed in detail in this proposal in which Raman spectroscopy and genetic engineering can be optimally used include investigating the mechanism of active transport in bacteriorhodopsin, visual transduction in photoreceptor membrane, ornithine transcarbamoylase enzymatic catalysis, calmodulin calcium interaction and DNA-aflatoxin binding. There exists at Boston University an extensive infrastructure for the utilization of Raman spectroscopy to investigate biomolecular structure. However, the current Raman instrumentation is over 15 years old, not available on a full-time basis and inadequate for the proposed research. The acquisition of a modern laser Raman facility for biomolecular studies would have a major impact on several NIH sponsored research programs. The proposed Raman facility would facilitate research in several new directions. It features OMA detection in the UV-visible region; time-resolution down to nanoseconds, temperature control of samples from 77 K to the physiological range; spinning-cell Raman-difference spectroscopy and visible-UV kinetic absorption and fluorescence capability. An important feature of the proposed facility are two ion lasers for pump-probe experiments and a Nd:YAG pulsed laser to provide rapid excitation necessary for time-resolved experiments.